Herbicide Compatibility Improvement

ABSTRACT

A herbicidal composition comprises an aqueous solution of a plurality of salts of glyphosate wherein said glyphosate is in anionic form accompanied by low molecular weight non-amphiphilic cations, wherein a major amount but less than 100% of the low molecular weight non-amphiphilic cations are potassium cations, and wherein the composition has a measured pH of at least about 4.8.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation application of U.S. patentapplication Ser. No. 15/702,432, filed Sep. 12, 2017, which is acontinuation application of U.S. patent application Ser. No. 13/942,188,filed Jul. 15, 2013, which is a continuation application of U.S. patentapplication Ser. No. 13/550,108, filed on Jul. 16, 2012 (now U.S. Pat.No. 8,492,309), which is a divisional application of U.S. patentapplication Ser. No. 11/438,573, filed on May 22, 2006 (now U.S. Pat.No. 8,236,731), which claims the benefit of and priority to U.S.provisional application Ser. No. 60/684,024, filed on May 24, 2005. Theentire disclosures of each of these applications are incorporated hereinby reference.

FIELD OF THE INVENTION

The present invention relates to methods and compositions that improvecompatibility of herbicides when mixed, for example in a spray tank. Inparticular, the invention relates to compatibility in a tank mixture ofaqueous formulations of herbicides that are in the form of salts, moreparticularly where the mixture comprises salts of glyphosate and aphenoxy-type herbicide.

BACKGROUND OF THE INVENTION

Economics of distribution of agricultural chemicals, such as herbicidesin general and glyphosate formulations in particular, can be muchimproved through provision of a high “loading” of active ingredient inthe formulation, that is, the amount of active ingredient that can beaccommodated in a container of given capacity.

Glyphosate is an acid that is relatively insoluble in water (1.16% byweight at 25° C.). For this reason it is typically formulated as awater-soluble salt in aqueous solution. A useful alternative is toprepare glyphosate as a dry salt in powder or granular form. Forexample, a dry water-soluble granular formulation of glyphosate ammoniumsalt can have a glyphosate acid equivalent (a.e.) content as high asabout 86% by weight. This would appear at first sight to provide anexcellent solution to the challenge of packing more glyphosate into acontainer of given capacity. Unfortunately the benefit of a dryglyphosate formulation in this regard is more limited than one mightexpect, because such a formulation tends to have low bulk density. Also,many end-users and many distributors prefer a liquid product because offlexibility in handling, thus a need remains for high-loaded liquidformulations of glyphosate.

U.S. Pat. No. 6,544,930 to Wright discloses an approach to meeting thischallenge. According to this approach, a concentrated aqueous solutionof glyphosate, predominantly in the form of one or a mixture of thepotassium and monoethanolammonium (MEA) salts thereof, was provided, ithaving been determined that such a solution had an unexpectedly highspecific gravity, permitting more glyphosate a.e. to be delivered in acontainer of given capacity than was previously attainable using theisopropylammonium (IPA) salt in widespread commercial use, for exampleas Roundup® herbicide of Monsanto.

Unfortunately, glyphosate potassium salt, especially when formulated athigh concentration in aqueous solution, brings some challenges of itsown. For example, where (as often) it is desired to coformulate asurfactant with the glyphosate, physical incompatibility of thesurfactant with the glyphosate salt can limit the options available.Whereas a range of surfactants are compatible with glyphosate IPA salt,fewer have been found to be compatible with glyphosate potassium salt,in particular where the salt is present at high concentration. Seeabove-cited U.S. Pat. No. 6,544,930, col. 9, lines 6-13.

Another challenge arises where a user of a glyphosate potassium saltformulation wishes to add to that formulation, with dilution in water(for example in a spray tank) a second herbicide that is also in a formof a salt, for example a phenoxy-type herbicide salt such as an organicammonium, illustratively dimethylammonium (DMA) salt of2,4-dichlorophenoxyacetic acid (2,4-D), to form a tank mixture. Suchtank mixtures of glyphosate and phenoxy-type herbicides are widely used,but their use can be limited by a tendency, under certain conditions,for precipitation of solids that can settle and clog filters or nozzlesof field spraying equipment. This tendency is evidence of physicalincompatibility of the glyphosate salt and the phenoxy-type herbicidesalt under such conditions.

International Patent Publication No. WO 03/013241 proposes, inter alia,a glyphosate composition comprising IPA and potassium cations in a moleratio of 1:10 to 30:1, “more preferably less than 15:1 and greater than1:2”, reportedly as a means to improve bioefficacy over compositions ofa single glyphosate salt.

U.S. Patent Application Publication No. 2003/0125209 states thatviscosity of concentrated glyphosate IPA formulations can be reduced byusing a lower molar excess of IPA than a 15-20% molar excess, saidtherein to be “typical”. A glyphosate/IPA mole ratio “between about1.00:1.00 and about 1:00:1.10 . . . , preferably between 1:00:1.00 andabout 1.00:1.05” is proposed therein.

Publications cited above are incorporated herein by reference.

Considering the variety of conditions and special situations under whichglyphosate herbicides are used around the world, there remains a needfor aqueous concentrate formulations of glyphosate, includingsurfactant-containing formulations, providing benefits under at leastsome of those conditions and situations. There is an especial need forsuch formulations having high glyphosate loading, for example at leastabout 400 g a.e./l, that are compatible when tank mixed withphenoxy-type herbicide salts under a wide range of field conditions.

SUMMARY OF THE INVENTION

A “glyphosate potassium salt” formulation herein is a glyphosate saltformulation wherein a major amount to substantially all of thesalt-forming cations are potassium cations. Other salt-forming cations,such as ammonium and organic ammonium cations, are optionally present insuch a formulation to a minor degree, for example not more than about50%, typically not more than about 30%, by molar amount of allsalt-forming cations present.

It has now surprisingly been found that a small increase in the molarexcess of cations in a glyphosate potassium salt formulation can resultin improved tank-mix compatibility of such a formulation with aphenoxy-type herbicide salt. Too great an increase in the molar excessof cations can result in reduced surfactant compatibility, as evidencedby a lowering of cloud point to an unacceptable level; thus, where asurfactant is included in the glyphosate salt formulation, it isimportant not to exceed a maximum molar excess consistent withacceptable cloud point.

Even more surprisingly, it has now been found that where cations addedto a glyphosate potassium salt formulation to achieve molar excess areorganic ammonium (e.g., IPA) cations rather than potassium cations,tank-mix compatibility at equivalent molar excess can be furtherimproved.

Accordingly, there is now provided a herbicidal composition comprisingin aqueous solution one to a plurality of salts of glyphosate at a totalglyphosate a.e. concentration not less than about 360 g/l, wherein (a)said glyphosate is in anionic form accompanied by low molecular weightnon-amphiphilic cations in a total molar amount of about 110% to about120% of the molar amount of said glyphosate; and (b) a major amount tosubstantially all of the low molecular weight non-amphiphilic cationsare potassium cations. The composition exhibits improved tank-mixcompatibility with a phenoxy-type herbicide salt formulation bycomparison with an otherwise similar composition having a lower molaramount of said low molecular weight non-amphiphilic cations.

There is also provided a composition as just described, furthercomprising at least one surfactant, wherein the weight ratio ofglyphosate (expressed as a.e.) to surfactant is not greater than about10:1.

In an embodiment of the invention, the composition comprises a mixtureof potassium and low molecular weight organic ammonium salts ofglyphosate wherein the mole ratio of potassium to low molecular weightorganic ammonium cations is about 55:45 to about 99:1.

In a further embodiment, the composition comprises glyphosate potassiumsalt having no more than a pH adjusting amount of low molecular weightorganic ammonium cations. A “pH adjusting amount” in the present contextmeans an amount sufficient to raise pH of a glyphosate potassium saltsolution, as determined by a method substantially as taught herein, byup to about 0.5 pH unit.

A tank-mix herbicidal composition, prepared by admixing a glyphosatesalt composition as provided above and a phenoxy-type herbicide salt ina glyphosate to phenoxy-type herbicide a.e. ratio of about 1:5 to about20:1, is also an embodiment of the present invention. Accordingly, thereis provided a tank-mix herbicidal composition comprising, in an aqueousapplication medium, a glyphosate herbicide and a phenoxy-type herbicide,the composition being prepared by a process comprising admixing in asuitable vessel with agitation:

-   -   (i) water in an amount suitable for application to a plant        and/or soil surface by spraying;    -   (ii) a herbicidally effective amount of a first aqueous        concentrate herbicidal composition comprising in aqueous        solution one to a plurality of salts of glyphosate at a total        glyphosate a.e. concentration not less than about 360 g/l,        wherein (a) said glyphosate is in anionic form accompanied by        low molecular weight non-amphiphilic cations in a total molar        amount of about 110% to about 120% of the molar amount of said        glyphosate; and (b) a major amount to substantially all of the        low molecular weight non-amphiphilic cations are potassium        cations; and    -   (iii) a second aqueous concentrate herbicidal composition        comprising in aqueous solution one to a plurality of salts of        the phenoxy-type herbicide, in an amount providing a glyphosate        to phenoxy-type herbicide a.e. ratio of about 1:5 to about 20:1.

There is still further provided a process for preparing a tank-mixherbicidal composition, the process comprising admixing in a suitablevessel with agitation:

-   -   (i) water in an amount suitable for application to a plant        and/or soil surface by spraying;    -   (ii) a herbicidally effective amount of a first aqueous        concentrate herbicidal composition comprising in aqueous        solution one to a plurality of salts of glyphosate at a total        glyphosate a.e. concentration not less than about 360 g/l,        wherein (a) the glyphosate is in anionic form accompanied by low        molecular weight non-amphiphilic cations in a total molar amount        of about 110% to about 120% of the molar amount of glyphosate;        and (b) a major amount to substantially all of the low molecular        weight non-amphiphilic cations are potassium cations; and    -   (iii) a second aqueous concentrate herbicidal composition        comprising in aqueous solution one to a plurality of salts of        the phenoxy-type herbicide, in an amount providing a glyphosate        to phenoxy-type herbicide a.e. ratio of about 1:5 to about 20:1.

There is still further provided a method for improving compatibility ofan aqueous concentrate glyphosate potassium salt composition with anaqueous concentrate phenoxy-type herbicide salt composition when admixedwith water to form a tank-mix composition, the method comprising addinga base in an amount sufficient to raise pH of the tank-mix compositionto at least about 4.8.

There is still further provided a method for redissolving a precipitatethat forms when an aqueous concentrate glyphosate potassium saltcomposition and an aqueous concentrate phenoxy-type herbicide saltcomposition are admixed with water to form a tank-mix composition, themethod comprising adding a base in an amount sufficient to redissolvethe precipitate.

There is still further provided a process for preparing an aqueousconcentrate glyphosate salt composition, the process comprising:

-   -   (i) neutralizing glyphosate acid with potassium hydroxide and        optionally a minor amount of a low molecular weight organic        amine in presence of water to produce a slurry or concentrated        glyphosate salt solution having a pH of about 4.4 to about 4.7;    -   (ii) adding water if necessary and optionally at least one        surfactant to produce a final composition having a total        glyphosate a.e. concentration not less than about 360 g/l; and    -   (iii) adding a low molecular weight organic amine in an amount        sufficient to provide a pH of about 4.8 to about 5.0 in the        final composition;        wherein the low molecular weight organic amine is added before,        during or after addition of the water to produce the final        composition.

DETAILED DESCRIPTION

A herbicidal composition of one embodiment of the invention comprises inaqueous solution one to a plurality of salts of glyphosate at a totalglyphosate a.e. concentration not less than about 360 g/l. Theglyphosate is in anionic form accompanied by low molecular weightnon-amphiphilic cations in a total molar amount of about 110% to about120% of the molar amount of the glyphosate. A major amount tosubstantially all of the low molecular weight non-amphiphilic cationsare potassium cations.

By “total glyphosate a.e. concentration” is meant the concentration ofglyphosate in all forms present, expressed as acid equivalent. An upperlimit for such concentration is dictated by the limit of solubility ofthe particular salt or mixture of salts present, but in absence of otheringredients such as a surfactant a total glyphosate a.e. concentrationof up to about 650 g/l or even higher can be achieved in some instances.In presence of surfactant, a practical upper limit is typically about600 to about 620 g/1.

In various embodiments the total glyphosate a.e. concentration in thecomposition is not less than about 400 g/l, not less than about 450 g/l,not less than about 480 g/l, or not less than about 540 g/l.

A “low molecular weight non-amphiphilic cation” herein is distinguishedfrom higher molecular weight cationic entities that can be contributedby certain surfactants such as polyoxyethylene tertiary amines,etheramines and quaternary ammonium surfactants. It will be understood,therefore, that such higher molecular weight entities, even if present,are not to be included in any calculation of molar amount of cations forpurposes of the invention. Low molecular weight non-amphiphilic cationsillustratively include alkali metal cations such as potassium and sodiumcations, ammonium cations, low molecular weight organic ammonium cationssuch as methylammonium, dimethylammonium, propylammonium(n-propylammonium and isopropylammonium), mono-, di- andtriethanolammonium cations, and low molecular weight organic sulfoniumcations such as trimethylsulfonium cations.

In the present compositions, at least a major amount (i.e., more than 50mole %) of the low molecular weight non-amphiphilic cations arepotassium cations. In various embodiments, at least about 55 mole %, atleast about 60 mole %, at least about 65 mole %, at least about 70 mole%, at least about 75 mole %, at least about 80 mole %, at least about 85mole % or at least about 90 mole % of the low molecular weightnon-amphiphilic cations are potassium cations.

Where potassium cations constitute less than 100% of all low molecularweight non-amphiphilic cations present in the composition, the balancecan be provided by any one or more such cations other than potassium,including without limitation those mentioned above. In one embodiment,the balance is provided in part or in whole by low molecular weightorganic ammonium cations. In various embodiments a mole ratio ofpotassium to organic ammonium cations of about 55:45 to about 99:1,about 60:40 to about 99:1, about 70:30 to about 99:1, about 55:45 toabout 95:5, about 60:40 to about 95:5, about 70:30 to about 95:5, about55:45 to about 90:10, about 60:40 to about 90:10 or about 70:30 to about90:10 is present.

In more specific embodiments, the organic ammonium cations if presentcomprise propylammonium cations. In even more specific embodiments, theorganic ammonium cations if present comprise isopropylammonium (IPA)cations.

Optionally more than one species of low molecular weight organicammonium cations can be present, in any suitable ratio.

In selecting a suitable mole ratio of potassium to organic ammoniumcations, it may be helpful to note that at a mole ratio substantiallylower than about 70:30, it becomes more difficult to provide acomposition with high glyphosate loading as desired herein; and that ata mole ratio higher than about 90:10, surfactant compatibility, asmeasured for example by cloud point, can be reduced. It will berecognized that not all surfactants give rise to cloud point problems;glyphosate formulations with alkyl polyglucosides (APGs), for example,typically do not exhibit a cloud point.

In a composition comprising potassium and IPA cations, the mole ratio ofpotassium to IPA cations in various non-limiting embodiments is about70:30 to about 90:10, about 75:25 to about 85:15 or about 77:23 to about83:17, for example about 80:20. Illustratively, a suitable potassium/IPAmole ratio can be about 2.5:1 to about 7.5:1, i.e., about 71:29 to about88:12, for example about 3:1 to about 6:1, i.e., about 75:25 to about86:14).

The low molecular weight non-amphiphilic cations in total constituteabout 110% to about 120% of the molar amount of the glyphosate in thecomposition. In other words, the composition has a “base excess” ofabout 10% to about 20%.

The pH of the composition is an indicator of the level of base excess.However, pH is difficult to measure to the degree of accuracy needed toprecisely determine the level of base excess, and a measured pH value ofa given composition can depend on the precise protocol followed inmaking the measurement. As guidance, however, a composition having a pHnot lower than about 4.8, as determined by a procedure substantially asdescribed below, will generally be found suitable. Illustratively, thepH can be about 4.8 to about 7.0, for example about 4.8 to about 6.0,about 4.8 to about 5.0, about 4.85 to about 4.99 or about 4.9 to about4.98.

Measurement of pH can be according to any suitable protocol. Forexample, a sample of a test formulation of known weight is diluted indemineralized water to make a total solution mass of, say, 100 g, whichis agitated, e.g., with a magnetic stirring bar. A pH meter capable ofmeasuring pH to at least 2 decimal places, and fitted with an electrodewith temperature compensation, is calibrated with standard buffers, forexample at pH 4.0 and pH 7.0. The solution pH is recorded when a stablereading is obtained. Between sample measurements, the electrode shouldbe washed with and stored temporarily in demineralized water. After allsample measurements, the calibration is rechecked against the standardbuffers. Illustration of use of such a protocol is found in Example 9hereinbelow.

Because of the vagaries of pH determination, it is possible that acomposition having a level of base excess as recited herein has ameasured pH slightly outside the ranges given above for guidance. Insuch a case, base excess or mole ratio as determined analytically or bystoichiometry from formulation records will be understood to bedispositive.

Commercial formulations based on glyphosate IPA salt commonly have abase excess of no more than about 5% to about 10%, and the activeingredient of such formulations is often referred to as“mono(isopropylammonium) glyphosate” to reflect a glyphosate/IPA moleratio close to 1:1. Increasing the mole ratio of anions to cationssubstantially above 1:1.2 (i.e., providing a base excess substantiallygreater than 20%) not only adds unnecessary cost through the resultingexcess of the cationic species used, but can reduce the upper limit ofsolubility of the salt mixture, especially in presence of surfactant.According to the present invention, a minimum of about 10% base excessis desirable to enhance tank-mix compatibility with phenoxy-typeherbicide salts. Thus, for practice of the invention, the total molaramount of low molecular weight non-amphiphilic cations should be about110% to about 120% of the molar amount of glyphosate. In variousembodiments, the base excess can be about 12% to about 20%, about 15% toabout 20%, about 12% to about 18% or about 15% to about 18%.

In one embodiment, the composition is based predominantly on glyphosatepotassium salt, but low molecular weight organic ammonium cations, forexample propylammonium such as IPA cations, are present in no more thana pH adjusting amount as defined hereinabove. The amount of such organicammonium cations can, in various embodiments, be sufficient to raise pHby about 0.1 to about 0.5 units, for example about 0.2 to about 0.5units, in a pH range from about 4.4 to about 5.0. A molar ratio ofpotassium to low molecular weight organic ammonium cations of about 95:5to about 99:1, for example about 96:4 to about 98:2, illustrativelyabout 97:3, will generally be found suitable.

While a composition of the invention can consist essentially of nothingmore than the above-described glyphosate salt or mixture of glyphosatesalts in aqueous solution, advantages of the invention becomeparticularly great when one or more surfactants are also included in thecomposition in an agronomically useful amount.

An “agronomically useful amount” means a sufficient amount of thesurfactant or surfactants to provide a benefit in terms of improvedherbicidal effectiveness by comparison with an otherwise similarglyphosate composition lacking surfactant. What constitutes anagronomically useful amount depends on the particular surfactant(s)selected, the plant species to be treated with the herbicidalcomposition, application spray volume, environmental and other factors.Typically a minimum agronomically useful amount is about 1 part byweight of total surfactant per 10 parts by weight of glyphosate acidequivalent.

Thus, in one embodiment, a herbicidal composition is provided asdescribed hereinabove, further comprising at least one surfactant,wherein the weight ratio of glyphosate a.e. to total surfactant is notgreater than about 10:1, for example about 2:1 to about 10:1.Illustratively the weight ratio of glyphosate a.e. to total surfactantis about 2.5:1 to about 8:1, for example about 3:1 to about 6:1.

The choice of surfactant or surfactants is not narrowly critical. One ofordinary skill in the art will be able to select a suitable surfactantor surfactant blend from among those known to enhance herbicidaleffectiveness of glyphosate by routine experimentation based upon theinformation provided herein and in the literature pertaining toglyphosate formulations. See, for example, surfactants disclosed ascomponents of glyphosate formulations in the patents and publicationsindividually cited below, each incorporated herein by reference.

U.S. Pat. No. 6,455,473 to Wright.

International Patent Publication No. WO 99/21424.

International Patent Publication No. WO 01/89302.

Above-cited WO 03/013241.

The surfactant(s) can be present in solution (e.g., micellar solution)and/or in stable dispersion, for example as a suspension, emulsion ormicroemulsion, in the composition.

A surfactant that is a “major or sole surfactant component” hereinconstitutes about 50% to 100% by weight of all surfactants present inthe composition. For the present purpose, the weight or concentration ofa surfactant component as defined herein does not includenon-amphiphilic compounds that are sometimes introduced with thesurfactant component, such as water, isopropanol or other solvents, orglycols, such as ethylene glycol, propylene glycol or polyethyleneglycols.

In one embodiment the composition comprises one or more surfactants eachhaving a molecular structure comprising:

-   -   (a) a hydrophobic moiety having one to a plurality of aliphatic,        alicyclic or aromatic C₃₋₁₈ hydrocarbyl or hydrocarbylidene        groups joined together by 0 to about 7 linkages selected from        ether, thioether, sulfoxide, ester, thioester and amide        linkages, the hydrophobic moiety having in total about 8 to        about 24 carbon atoms; and    -   (b) a hydrophilic moiety that comprises:        -   (i) an amino group that is cationic or that can be            protonated to become cationic, having attached directly            thereto 0 to 3 oxyethylene groups or polyoxyethylene chains,            such oxyethylene groups and polyoxyethylene chains            comprising on average no more than about 15 oxyethylene            units per surfactant molecule; and/or        -   (ii) a glycoside or polyglycoside group comprising on            average no more than about 2 glycoside units per surfactant            molecule;            the hydrophobic moiety being covalently attached (1)            directly to an amino group of the hydrophilic moiety; (2) by            an ether linkage incorporating an oxygen atom of an            oxyethylene group or of a terminal oxyethylene unit of a            polyoxyethylene chain of the hydrophilic moiety; or (3) by            an ether linkage to a glycoside unit of the hydrophilic            moiety.

According to the present embodiment, two subclasses of surfactant,defined by formulas (I) and (II) below, can be particularly useful.

A major or sole surfactant component can comprise one or more compoundshaving, at a pH of about 4, formula (I):

[R¹—(XR²)_(m)—(OCH₂CH₂)_(n)—(NR³R⁴—(CH₂)_(p))_(q)-(glu)_(r)OH]_(s)[A]_(t)  (I)

where R¹ is hydrogen or C₁₋₁₈ hydrocarbyl, each X is independently anether, thioether, sulfoxide, ester, thioester or amide linkage, each R²is independently C₃₋₆ hydrocarbylidene, m is an average number of 0 toabout 8 such that the total number of carbon atoms in R¹—(XR²)_(m) isabout 8 to about 24, n is an average number of 0 to about 5, R³ and R⁴are independently hydrogen or C₁₋₄ alkyl, p is 2 to 4, q is 0 or 1, gluis a unit of formula

(referred to herein as a glucoside unit), r is an average number ofabout 1 to about 2, A is an anionic entity, and s is an integer of 1 to3 and t is 0 or 1 such that electrical neutrality is maintained.

A major or sole surfactant component can comprise one or more compoundshaving, at a pH of about 4, formula (II):

where R¹, X, R², m, n, A, s and t are as defined above for formula (I),R⁵ is hydrogen, C₁₋₄ alkyl, benzyl, an anionic oxide group or an anionicgroup —(CH₂)_(u)C(O)O where u is 1 to 3, R⁶ and R⁷ are independentlyhydrogen, C₁₋₄ alkyl, C₂₋₄ acyl or C₁₋₄ carboxylic acid groups or C₁₋₄alkyl esters of C₁₋₄ carboxylic acid groups, and x and y are averagenumbers such that x+y+n is not greater than about 15.

Surfactants conforming to formulas (I) and (II) above include withoutrestriction those that are or can be described as alkyl polyglucosides,alkylaminoglucosides, polyoxyethylene alkylamines, polyoxyethylenealkyletheramines, alkyltrimethylammonium salts,alkyldimethylbenzylammonium salts, polyoxyethylene N-methylalkylammonium salts, polyoxyethylene N-methyl alkyletherammonium salts,alkyldimethylamine oxides, polyoxyethylene alkylamine oxides,polyoxyethylene alkyletheramine oxides, alkylbetaines,alkylamidopropylamines and the like. The word or part-word “alkyl” asused in this paragraph reflects common usage in the art and means C₈₋₁₈aliphatic, saturated or unsaturated, linear or branched hydrocarbyl.

When a maximum or minimum “average number” is recited herein withreference to a structural feature of a surfactant such as oxyethylene orglucoside units, it is to be understood that the integer number of suchunits in individual molecules in a surfactant preparation typicallyvaries over a range that can include integer numbers greater than themaximum “average number” or smaller than a nonzero minimum “averagenumber”. The presence in a composition of individual surfactantmolecules having an integer number of such units outside the statedrange of “average number” does not remove the composition from the scopeof the present embodiments, so long as the “average number” is withinthe stated range and other requirements are met.

Illustrative surfactant types that can be useful in compositions of theinvention include those classified as types A to F below.

Type A: surfactants corresponding to formula (I) where R¹ is a C₈₋₁₈aliphatic hydrocarbyl chain, m, n and q are 0, s is 1 and t is 0. Thistype includes several commercial surfactants collectively known in theart or referred to herein as alkyl polyglucosides or APGs. Suitableexamples are sold by Cognis as Agrimul™ PG-2069 and Agrimul™ PG-2067.

Type B: surfactants corresponding to formula (II) where R¹ is a C₈₋₁₈aliphatic hydrocarbyl chain and m is 0. In this type R¹ alone can beconsidered the hydrophobic moiety of the surfactant and is attacheddirectly to the amino function, as in alkylamines, or by an etherlinkage formed by the oxygen atom of an oxyethylene group or theterminal oxygen atom of a polyoxyethylene chain, as in certainalkyletheramines. Illustrative subtypes having different hydrophilicmoieties include those classified as subtypes B1 to B5 below.

Subtype B1: x and y are 0, R⁵ and R⁶ are independently C₁-4 alkyl, R⁷ ishydrogen and t is 1. This subtype includes (where R⁵ and R⁶ are methyl)several commercial surfactants collectively known in the art or referredto herein as alkyldimethylamines. Suitable examples aredodecyldimethylamine, available for example from Akzo-Nobel as Armeen™DM12D, and cocodimethylamine and tallowdimethylamine, available forexample from Ceca as Noram™ DMC D and Noram™ DMS D respectively. Suchsurfactants are generally provided in non-protonated form, the anion Anot being supplied with the surfactant. However, in a glyphosate saltformulation at a pH of about 4-5, the surfactant will be protonated andit will be recognized that the anion A can be glyphosate, which iscapable of forming dibasic salts.

Subtype B2: x and y are 0, R⁵, R⁶ and R⁷ are independently C₁-4 alkyland t is 1. This subtype includes (where R⁵, R⁶ and R⁷ are methyl and Ais a chloride ion) several commercial surfactants collectively known inthe art or referred to herein as alkyltrimethylammonium chlorides. Asuitable example is cocoalkyl trimethylammonium chloride, available forexample from Akzo-Nobel as Arquad™ C.

Subtype B3: x and y are average numbers such that x+y is at least 2, R⁶and R⁷ are hydrogen and t is 1. This subtype includes commercialsurfactants collectively known in the art or referred to herein aspolyoxyethylene alkylamines (where n is 0 and R⁵ is hydrogen), certainpolyoxyethylene alkyletheramines (where n is 1-5 and R⁵ is hydrogen),polyoxyethylene N-methyl alkylammonium chlorides (where n is 0, R⁵ ismethyl and A is a chloride ion), and certain polyoxyethylene N-methylalkyletherammonium chlorides (where n is 1-5, R⁵ is methyl and A is achloride ion). Suitable examples are polyoxyethylene (2) cocoamine,polyoxyethylene (5) tallowamine and polyoxyethylene (10) cocoamine,available for example from Akzo-Nobel as Ethomeen™ C/12, Ethomeen™ T/15and Ethomeen™ C/20 respectively; a surfactant conforming, when its aminegroup is non-protonated, to formula (III):

where R¹ is C₁₂-14 alkyl, n is 3 and x+y has an average value of about5, as disclosed in U.S. Pat. No. 5,750,468 to Wright et al.,incorporated herein by reference; and polyoxyethylene (2) N-methylcocoammonium chloride and polyoxyethylene (2) N-methyl stearylammoniumchloride, available for example from Akzo-Nobel as Ethoquad™ C/12 andEthoquad™ 18/12 respectively. In cases where R⁵ is hydrogen, i.e., intertiary amine as opposed to quaternary ammonium surfactants, the anionA is typically not supplied with the surfactant. However, in aglyphosate salt formulation at a pH of about 4-5, the surfactant will beprotonated and it will be recognized that the anion A can be glyphosate,which is capable of forming dibasic salts. In one sub-embodiment a soleor major surfactant component is a polyoxyethylene alkylamine surfactantwherein n is 0 and x+y is 2 to about 8, as disclosed in U.S. Pat. No.5,668,085 to Forbes et al., incorporated herein by reference.

An illustrative surfactant useful in a composition of the invention is apolyoxyethylene fatty amine having about 7 to about 15 EO units,optionally in a blend with a polyoxyethylene fatty amine having about 2to about 5 EO units. Such fatty amines can, without limitation,independently be selected from tallowamines, hydrogenated tallowamines,stearylamines, oleylamines, cetylamines, myristylamines, soyamines,cocoamines, laurylamines and mixtures thereof. For example, a high-EOtallowamine such as one having about 7.5, about 8, about 8.5, about 9,about 9.5, about 10, about 10.5, about 11, about 11.5, about 12, about12.5, about 13, about 13.5, about 14, about 14.5 or about 15 EO unitscan optionally be blended with a low-EO cocoamine such as one havingabout 2, about 2.5, about 3, about 3.5, about 4, about 4.5 or about 5 EOunits. Either or both of the tallowamine and the cocoamine components ofsuch a blend can optionally be substituted, in whole or in part, withanother fatty amine, for example a soyamine component. A suitable weightratio of high-EO to low-EO fatty amine in such a blend can be, forexample, about 50:50, about 55:45, about 60:40, about 65:35, about70:30, about 75:25, about 80:20, about 85:15 or about 90:10.

In a variant of subtype B3, R⁶ and R⁷ are other than hydrogen. Forexample, the surfactant of formula (III) is a member of a classconforming to formula (Ma):

where R¹, n, x and y are as defined above, and R⁶ and R⁷ areindependently selected from hydrogen, C₁₋₄ alkyl, C₂₋₄ acyl and C₁₋₄carboxylic acid groups and C₁₋₄ alkyl esters of C₁₋₄ carboxylic acidgroups. Illustratively R⁶ and R⁷ are the same and are selected from —H,—CH₃, —C₂H₅, —CH(CH₃)₂, —COOH, —COOCH₃, —COOC₂H₅, —CH₂COOH, —CH₂COOCH₃and —CH₂COOC₂H₅ groups.

Subtype B4: R⁵ is an anionic oxide group and t is 0. This subtypeincludes commercial surfactants collectively known in the art orreferred to herein as alkyldimethylamine oxides (where n, x and y are 0,and R⁶ and R⁷ are methyl), alkyletherdimethylamine oxides (where n is1-5, x and y are 0, and R⁶ and R⁷ are methyl), polyoxyethylenealkylamine oxides (where n is 0, x+y is at least 2, and R⁶ and R⁷ arehydrogen), and certain polyoxyethylene alkyletheramine oxides (where nis 1-5, x+y is at least 2, and R⁶ and R⁷ are hydrogen). Suitableexamples are cocodimethylamine oxide and polyoxyethylene (2) cocoamineoxide, available for example from Akzo-Nobel as Aromox™ DMC and Aromox™C/12 respectively.

Subtype B5: R⁵ is an acetate group, x and y are 0 and t is 0. Thissubtype includes commercial surfactants collectively known in the art orreferred to herein as alkylbetaines (where n is 0 and R⁶ and R⁷ aremethyl) and certain alkyletherbetaines (where n is 1-5 and R⁶ and R⁷ aremethyl). A suitable example is cocobetaine, available for example fromCognis as Velvetex™ AB-45.

Type C: surfactants corresponding to formula (II) where R¹ is a C₈₋₁₈aliphatic hydrocarbyl chain, m is 1, X is an ether linkage, R² isn-propylene and n is 0. In this type R¹ together with OR² can beconsidered the hydrophobic moiety of the surfactant which is attacheddirectly by the R² linkage to the amino function. These surfactants area subclass of alkyletheramines as disclosed in above-cited U.S. Pat. No.5,750,468. Illustrative subtypes have the different hydrophilic moietiesexemplified in subtypes B1 to B5 above. Suitable examples are asurfactant conforming, when its amine group is non-protonated, toformula (IV):

and a surfactant conforming to formula (V):

and a surfactant conforming to formula (VI):

where, in each of formulas (IV), (V) and (VI), R¹ is C₁₀₋₁₃ alkyl (e.g.,isodecyl, isotridecyl or cocoalkyl) and x+y has an average value ofabout 5, as disclosed in above-cited U.S. Pat. No. 5,750,468.

Type D: surfactants conforming to formula (II) where R¹ is a C₈₋₁₈aliphatic hydrocarbyl chain, m is 1-5, each XR² is a group —OCH(CH₃)CH₂—and n is 0. In this type R¹ together with the —OCH(CH₃)CH₂— group(s) canbe considered the hydrophobic moiety of the surfactant which is attacheddirectly to the amino function. These surfactants are a further subclassof alkyletheramines as disclosed in above-cited U.S. Pat. No. 5,750,468.Illustrative subtypes have the different hydrophilic moietiesexemplified in subtypes B1 to B5 above. A suitable example is asurfactant conforming, when its amine group is non-protonated, toformula (VII):

where R¹ is C₁₂₋₁₅ alkyl and x+y has an average value of about 5, asdisclosed in above-cited U.S. Pat. No. 5,750,468.

The surfactant of formula (VII) is a member of a class conforming toformula (VIIa):

where R¹, x and y are as defined above, and R⁶ and R⁷ are independentlyselected from hydrogen, C₁₋₄ alkyl, C₂₋₄ acyl and C₁₋₄ carboxylic acidgroups and C₁₋₄ alkyl esters of C₁₋₄ carboxylic acid groups.Illustratively R⁶ and R⁷ are the same and are selected from —H, —CH₃,—C₂H₅, —CH(CH₃)₂, —COOH, —COOCH₃, —COOC₂H₅, —CH₂COOH, —CH₂COOCH₃ and—CH₂COOC₂H₅ groups.

Another illustrative surfactant useful in a composition of the inventionis an etheramine surfactant similar to that of formula (VII) but whereinx+y has an average value of about 7 to about 15, for example about 7.5,about 8, about 8.5, about 9, about 9.5 or about 10. An example of such asurfactant wherein x+y has an average value of about 8 is referred toherein as “etheramine 8E0”. Such an etheramine can optionally be blendedwith a low-EO surfactant, for example a low-EO fatty amine surfactantsuch as a cocoamine having about 2, about 2.5, about 3, about 3.5, about4, about 4.5 or about 5 EO units, at a weight ratio of about 40:60 toabout 95:5, for example about 50:50, about 55:45, about 60:40, about65:35, about 70:30, about 75:25, about 80:20, about 85:15 or about90:10.

Type E: surfactants corresponding to formula (II) where R¹ is a C₈₋₁₈aliphatic hydrocarbyl chain, m is 1, X is an amide linkage, R² isn-propylene and n is 0. In this type R¹ together with XR² can beconsidered the hydrophobic moiety of the surfactant which is attacheddirectly by the R² linkage to the amino function. Commonly x and y are0, R⁵ is hydrogen or C₁₋₄ alkyl, R⁶ and R⁷ are independently C₁₋₄ alkyland t is 1. A suitable example is cocoamidopropyl dimethylaminepropionate, available for example from McIntyre as Mackalene™ 117.

Type F: surfactants corresponding to formula (II) where R¹ is hydrogen,m is 3-8 and each XR² is a group —OCH(CH₃)CH₂—. In this type thepolyether chain of —OCH(CH₃)CH₂— groups (a polyoxypropylene chain) canbe considered the hydrophobic moiety of the surfactant which is linkeddirectly or via one or more oxyethylene units to the amino function.Commonly x and y are 0, R⁵, R⁶ and R⁷ are independently C₁₋₄ alkyl and tis 1. Such surfactants are a subclass of polyoxypropylene quaternaryammonium surfactants as disclosed in U.S. Pat. No. 5,652,197 to Claudeet al., incorporated herein by reference. In a suitable example, m is 7,n is 1, R⁵, R⁶ and R⁷ are methyl and A is a chloride ion.

In surfactants of any of the above types where t is 1, A can be anysuitable anion, for example chloride, bromide, iodide, sulfate,ethosulfate, phosphate, acetate, propionate, succinate, lactate,citrate, tartrate or, as indicated above, glyphosate.

In another embodiment a major or sole surfactant component comprises anN—(C₈₋₁₈) acyl sarcosinate surfactant as disclosed in above-cited WO99/21424. Suitable examples are N-lauroyl, N-cocoyl, N-oleoyl andN-stearoyl sarcosinates.

In another embodiment at least one surfactant is present in thecomposition, selected from the group consisting of polyoxyethylene fattyamines having 2 to about 12 moles of ethylene oxide per mole of fattyamine, alkyletheramines, quaternary ammonium surfactants,polyoxyethylene alkylphenols, alkyl polyglycosides, alkylbetaines,alkylamine oxides and mixtures thereof.

Compositions of the invention can optionally contain additionalherbicidally inactive ingredients such as pH modulating agents (e.g.,acidifying, basifying and/or buffering agents), defoaming agents,antidrift agents, coloring agents, and the like. Such additionalingredients should be selected so as not to require reduction ofglyphosate a.e. concentration below about 360 g/l, nor significantlycompromise physical stability at high glyphosate a.e. concentration, norantagonize herbicidal activity of the composition to an unacceptabledegree.

Compositions of the invention can optionally contain one or moreadditional herbicides (i.e., other than glyphosate). In practice, at thehigh glyphosate a.e. concentrations of the present compositions, theamount of a second herbicide that can be accommodated in a stableformulation is rather limited, but in certain situations a small amountof a herbicide such as glufosinate, an imidazolinone or a sulfonylureacan be useful.

Highly concentrated aqueous glyphosate potassium salt compositionsexhibit relatively low viscosity and high density by comparison withglyphosate IPA salt compositions having equal glyphosate a.e.concentration. However, potassium glyphosate is much less compatiblewith a wide range of surfactants than IPA glyphosate, rendering thepotassium salt less useful for preparing surfactant-containingformulations with high glyphosate loading. By admixture of a relativelysmall amount of IPA glyphosate with potassium glyphosate, a highlyconcentrated aqueous glyphosate formulation can be prepared havingfavorable viscosity and density properties, yet capable of containing anagronomically useful amount of any of a wide range of surfactants thatare poorly compatible with potassium glyphosate alone.

An aqueous concentrate composition containing a mixture of potassium andIPA salts of glyphosate at a mole ratio of about 70:30 to about 90:10and at a total glyphosate a.e. concentration illustratively of about 400to about 600 g/l, with or without surfactant, can exhibit a lowerfreezing point than a comparative composition in which substantially allof the glyphosate is in the form of the potassium salt.

Furthermore, an aqueous concentrate composition containing a mixture ofpotassium and IPA salts of glyphosate at a mole ratio of about 70:30 toabout 90:10 and at a total glyphosate a.e. concentration illustrativelyof about 400 to about 600 g/l, with or without surfactant, can exhibit alower pour point than a comparative composition in which substantiallyall of the glyphosate is in the form of the potassium salt. By “pourpoint” is meant a temperature below which the composition is frozen ortoo viscous to be readily poured from a container.

Furthermore, an aqueous concentrate composition containing a mixture ofpotassium and IPA salts of glyphosate at a mole ratio of about 70:30 toabout 90:10 and at a total glyphosate a.e. concentration illustrativelyof about 400 to about 600 g/l, with or without surfactant, can exhibit,at any selected temperature above the pour point, lower viscosity than acomparative IPA salt composition. This is a particularly great advantagewhere large volumes of the concentrate composition are to be transferredby gravity or by pumping, especially at low temperatures as can occur inearly spring.

Mixed concentrated solutions of glyphosate potassium and IPA salts havebeen found to have lower viscosity than would be predicted from theviscosities of straight potassium salt and IPA salt solutions.

In various embodiments, a composition of the invention in absence ofsurfactant has a viscosity at 0° C. of not greater than about 300 cP,not greater than about 200 cP, not greater than about 150 cP, or notgreater than about 100 cP. At glyphosate a.e. loadings lower than about400 g/l, for example about 360 g/l, low temperature viscosity advantagesof a mixed salt formulation as described herein over a straight IPAglyphosate composition are less pronounced than at higher loadings, butcan still be sufficient to provide a useful benefit.

Furthermore, an aqueous concentrate composition containing a mixture ofpotassium and IPA salts of glyphosate at a mole ratio of about 70:30 toabout 90:10 and at a total glyphosate a.e. concentration of about 400 toabout 600 g/l, with or without surfactant, can exhibit higher densitythan a comparative IPA salt composition. Thus a given weight ofglyphosate a.e. can be accommodated in a lesser volume than is requiredfor the comparative composition. At glyphosate a.e. loadings lower thanabout 400 g/l, for example about 360 g/l, density advantages of a mixedsalt formulation as described herein over a straight IPA glyphosatecomposition are less pronounced than at higher loadings, but can stillbe sufficient to provide a useful benefit.

Surfactant incompatibility with a concentrated glyphosate salt solutioncan be expressed in various ways, but generally results in a loss ofphysical stability, at low or more particularly at high temperatures. Asglyphosate formulations are required to be stored in a wide range oftemperature conditions, such loss of physical stability is highlyundesirable.

A particularly useful measure of physical stability forsurfactant-containing aqueous concentrate formulations of glyphosatesalts is cloud point. Cloud point is a measure of the maximum or minimumtemperature at which a specific such formulation forms a single-phasesolution. At temperatures above a high temperature cloud point or belowa low temperature cloud point, the surfactant separates from thesolution, initially as a hazy or cloudy dispersion, and, upon standing,as a distinct phase generally rising to the surface of the solution. Theterm “cloud point” hereinbelow refers to a high temperature cloud pointunless the context demands otherwise.

Cloud point of a composition can be determined by heating thecomposition until the solution becomes cloudy, and then allowing thecomposition to cool, with agitation, while its temperature iscontinuously monitored. A temperature reading taken when the solutionclears is a measure of cloud point. What constitutes an acceptable cloudpoint is arbitrary, but for most purposes cloud point should be notlower than about 45° C., for example not lower than about 50° C., notlower than about 55° C., or not lower than about 60° C. Thus by onedefinition, a surfactant that is acceptably “compatible” in an aqueousconcentrate glyphosate composition of the invention is one that, whenpresent in a 360 g a.e./l composition at a glyphosate a.e./surfactantratio of 10:1 by weight, exhibits a cloud point not lower than about 45°C. Other, more stringent, definitions of compatibility can be set forthby specifying a higher glyphosate a.e. concentration, for example 400 ga.e./l, a lower glyphosate a.e./surfactant ratio (i.e., a highersurfactant concentration for a given glyphosate a.e. concentration)and/or a higher cloud point.

A number of surfactants that are known to be incompatible with potassiumglyphosate nonetheless exhibit acceptable cloud points in an aqueousconcentrate composition containing a mixture of potassium and IPA saltsof glyphosate at a mole ratio of about 70:30 to about 90:10 and at atotal glyphosate a.e. concentration of about 400 to about 600 g/l, insome cases when the glyphosate a.e./surfactant ratio is as low as 4:1.

As noted above, compositions of the invention exhibit improvedcompatibility when tank-mixed with a phenoxy-type herbicide saltformulation, as evidenced at least by a reduced tendency to form a solidprecipitate, or an increase in the time period needed for such aprecipitate to form after preparation of the tank-mix.

“Improved compatibility” in the present context is by comparison with aglyphosate composition similar in all respects to the composition of theinvention, except for the level of base excess. For example, aglyphosate potassium salt composition of the invention having about 10%to about 20% base excess exhibits improved compatibility with aphenoxy-type herbicide salt formulation by comparison with a comparativeglyphosate potassium salt composition having about 5% base excess.

“Tank-mixing” herein embraces any method in agricultural use wherein afirst herbicide composition and a second herbicide composition arediluted in water, in an amount suitable for application to a plantand/or soil surface by spraying, in any suitable vessel, most typicallyin a spray tank or in a pre-mixing tank. Order of addition of the waterand the first and second herbicide compositions is not critical. Mostcommonly, however, the user first adds a portion of the water to thevessel, then adds the two herbicide compositions with agitation, thenadds the remainder of the water, with continued agitation. Optionallyother ingredients such as ammonium sulfate, additional surfactant, ananti-foam agent and/or a spray drift reduction additive can be added toa tank-mix.

A “phenoxy-type” herbicide herein is a salt-forming herbicide having amode of action and/or selectivity towards broadleaved plant species thatis characteristic of phenoxy herbicides or similar thereto. “Phenoxyherbicides” herein are salt-forming herbicides that include withoutlimitation the following:

-   -   phenoxyacetic acids, for example:        -   4-chlorophenoxyacetic acid (4-CPA);        -   2,4-dichlorophenoxyacetic acid (2,4-D);        -   3,4-dichlorophenoxyacetic acid (3,4-DA);        -   4-chloro-2-methylphenoxyacetic acid (MCPA); and        -   2,4,5-trichlorophenoxyacetic acid (2,4,5-T);    -   phenoxypropanoic acids, for example:        -   2-(3-chlorophenoxy)propanoic acid (cloprop);        -   2-(4-chlorophenoxy)propanoic acid (4-CPP);        -   2-(2,4-dichlorophenoxy)propanoic acid (dichlorprop);        -   2-(3,4-dichlorophenoxy)propanoic acid (3,4-DP);        -   2-(2,4,5-trichlorophenoxy)propanoic acid (fenoprop); and        -   2-(4-chloro-2-methylphenoxy)propanoic acid (mecoprop); and    -   phenoxybutanoic acids, for example:        -   4-(4-chlorophenoxy)butanoic acid (4-CPB);        -   4-(2,4-dichlorophenoxy)butanoic acid (2,4-DB);        -   4-(3,4-dichlorophenoxy)butanoic acid (3,4-DB);        -   4-(4-chloro-2-methylphenoxy)butanoic acid (MCPB); and        -   4-(2,4,5-trichlorophenoxy)butanoic acid (2,4,5-TB);            including enantiomers (e.g., dichlorprop-P and mecoprop-P)            as well as racemates thereof.

Salt-forming herbicides that are not phenoxy herbicides in a strictsense but fall within the above definition of “phenoxy-type” herbicidesinclude without limitation the following:

-   -   benzoic acids, for example:        -   3-amino-2,5-dichlorobenzoic acid (chloramben);        -   3,6-dichloro-2-methoxybenzoic acid (dicamba);        -   2,3,6-trichlorobenzoic acid (2,3,6-TBA); and        -   2,3,5-trichloro-6-methoxybenzoic acid (tricamba);    -   picolinic acids, for example:        -   4-amino-3,6-dichloro-2-pyridinecarboxylic acid            (aminopyralid);        -   3,6-dichloro-2-pyridinecarboxylic acid (clopyralid); and        -   4-amino-3,5,6-trichloro-2-pyridinecarboxylic acid            (picloram); and    -   pyridinyloxyacetic acids, for example:        -   (3,5,6-trichloro-2-pyridinyl)oxyacetic acid (triclopyr);            including enantiomers as well as racemates thereof.

Among phenoxy-type herbicides, probably the most widely used in tank-mixwith glyphosate is 2,4-D.

Phenoxy-type herbicides in the form of any agriculturally acceptablesalt thereof, including potassium, sodium, ammonium and organic ammonium(more particularly low molecular weight organic ammonium) salts can betank-mixed with a glyphosate potassium salt formulation of theinvention. Low molecular weight organic ammonium salts include withoutlimitation methylammonium, dimethylammonium (DMA), propylammonium(n-propylammonium and isopropylammonium), mono-, di- andtriethanolammonium salts.

A phenoxy herbicide salt of particular interest is the DMA salt of2,4-D.

Methods of use of glyphosate herbicidal formulations are well known inthe art. An aqueous concentrate composition of the invention can bediluted in an appropriate volume of water to provide an applicationcomposition that can then be applied, for example by spraying, tofoliage of plants such as weeds to be killed or controlled. For mostpurposes, an application composition, for example a spray-tankcomposition, is applied at a glyphosate a.e. rate of about 0.1 to about5 kg/ha, occasionally more. Typical glyphosate a.e. rates for control ofannual and perennial grasses and broadleaved plants are about 0.3 toabout 1.5 kg/ha. A composition of the invention can be applied in anyconvenient volume of water, most typically about 50 to about 1,000 l/ha.

Likewise, methods of use of phenoxy-type herbicidal formulations arewell known in the art. Suitable application rates vary depending on theparticular phenoxy-type herbicide selected, the plant species to bekilled or controlled, and other factors. In general, a suitableapplication rate is about 0.1 to about 5 kg/ha. Illustratively, typicala.e. rates for control of annual and perennial broadleaved plants areabout 0.3 to about 2 kg/ha in the case of 2,4-D, about 0.2 to about 1kg/ha in the case of dicamba, and about 0.02 to about 0.2 kg/ha in thecase of picloram.

When tank-mixed with glyphosate, it is sometimes possible to reduce therate of the phenoxy-type herbicide needed to achieve acceptable weedcontrol. In general, suitable glyphosate/phenoxy-type herbicide a.e.ratios for tank-mixing are about 1:5 to about 20:1, depending again onthe particular phenoxy-type herbicide selected, the plant species to bekilled or controlled, and other factors. Illustratively, typical a.e.ratios are about 1:2 to about 5:1 in the case of 2,4-D, about 1:1 toabout 10:1 in the case of dicamba, and about 2:1 to about 20:1 in thecase of picloram.

A tank-mix herbicidal composition of the invention comprises, in anaqueous application medium, a glyphosate herbicide and a phenoxy-typeherbicide, the composition being prepared by a process comprisingadmixing in a suitable vessel with agitation:

-   -   (i) water in an amount suitable for application to a plant        and/or soil surface by spraying;    -   (ii) a herbicidally effective amount of a first aqueous        concentrate herbicidal composition comprising in aqueous        solution one to a plurality of salts of glyphosate at a total        glyphosate a.e. concentration not less than about 360 g/l,        wherein (a) the glyphosate is in anionic form accompanied by low        molecular weight non-amphiphilic cations in a total molar amount        of about 110% to about 120% of the molar amount of glyphosate;        and (b) a major amount to substantially all of the low molecular        weight non-amphiphilic cations are potassium cations; and    -   (iii) a second aqueous concentrate herbicidal composition        comprising in aqueous solution one to a plurality of salts of        the phenoxy-type herbicide, in an amount providing a glyphosate        to phenoxy-type herbicide a.e. ratio of about 1:5 to about 20:1.

Any glyphosate potassium salt composition (including those comprising aminor amount of a low molecular weight organic ammonium salt ofglyphosate) as described hereinabove can be used as the first aqueousconcentrate herbicidal composition according to the present embodiment.Any aqueous concentrate phenoxy-type herbicide salt formulation,including without limitation such formulations of any phenoxy-typeherbicide as mentioned hereinabove, can be used as the second herbicidalcomposition according to the present embodiment. The first (glyphosate)herbicidal composition is included in a herbicidally effective amount,for example an amount providing, when applied at a selected sprayvolume, an application rate of about 0.1 to about 5 kg a.e./ha, forexample about 0.3 to about 2.5 kg a.e./ha. The second (phenoxy-type)herbicidal composition is included in an amount providing a glyphosateto phenoxy-type herbicide a.e. ratio of about 1:5 to about 20:1, forexample about 1:2 to about 5:1 where the phenoxy-type herbicide is2,4-D, about 1:1 to about 10:1 where the phenoxy-type herbicide isdicamba, and about 2:1 to about 20:1 where the phenoxy-type herbicide ispicloram.

The tank-mix composition comprises water as a spray vehicle, in anamount suitable for application to a plant and/or soil surface byspraying, more particularly in an amount suitable for delivery of theglyphosate and phenoxy-type herbicides to plants, for example weeds,that are to be killed or controlled.

Amounts of water are usually expressed in terms of “spray volume”, i.e.,the volume of spray solution (which is mostly water, making up thebalance after accounting for the first and second herbicide compositionsand other optional additives as described below) to be applied to a unitland area. Spray volume can be expressed in any suitable units such asliters/hectare (l/ha) or gallons/acre. Most commonly, spray volumesuseful for tank-mix compositions of the present invention will beselected in a range of about 10 to about 1,000 l/ha, for example about25 to about 500 l/ha.

Tank-mix compatibility challenges using state-of-the-art glyphosatecompositions tend to be most severe at low spray volumes, where a spraysolution having higher concentrations of both the glyphosate and thephenoxy-type herbicides is prepared. Thus, while tank-mix compositionsof the present invention are useful at least across the wide range ofspray volumes indicated above, these compositions bring especial benefitat low to moderate spray volumes, such as, for example, spray volumes ofabout 10 to about 200 l/ha, illustratively about 25 to about 100 l/ha,for example about 46.8 l/ha (5 U.S. gallons/acre) or about 93.5 l/ha (10U.S. gallons/acre).

Tank-mix compatibility is also affected by aspects of water quality,especially water “hardness” resulting from presence of divalent andtrivalent cations, mainly calcium (Ca²⁺) and magnesium (Mg²⁺) ions.Hardness is often expressed as parts per million (ppm or mg/l) calciumcarbonate (CaCO₃), but typically includes all Ca²⁺ and Mg²⁺ ions,expressed as CaCO₃ equivalent concentration. Compatibility challengestend to be greatest in hard water, for example water having hardnessgreater than about 75 ppm, more particularly where greater than about150 ppm, especially where greater than about 300 ppm. Tank-mixcompositions of the present invention can generally be prepared usingwater of hardness up to about 1,000 ppm or even higher.

Commonly, users of glyphosate herbicides, in particular where tank-mixeswith a second herbicide are prepared, add an inorganic ammonium saltsuch as ammonium sulfate to the spray solution. Such addition isbelieved to have particular benefit in situations where water quality,including water hardness, is of concern. Accordingly, in one embodiment,a tank-mix composition as described above further comprises an inorganicammonium salt, for example ammonium sulfate. Illustratively, ammoniumsulfate can suitably be present in a tank-mix composition of the presentembodiment at a concentration of about 5 to about 50 g/l, for exampleabout 10 to about 20 g/1.

Other conventional additives to spray solutions, including additionalsurfactant(s), anti-foam agent(s), drift reduction additive(s),colorant(s), etc. can optionally be included in a tank-mix compositionof the invention.

A process of the invention for preparing a tank-mix herbicidalcomposition comprises admixing in a suitable vessel with agitation:

-   -   (i) water in an amount suitable for application to a plant        and/or soil surface by spraying;    -   (ii) a herbicidally effective amount of a first aqueous        concentrate herbicidal composition comprising in aqueous        solution one to a plurality of salts of glyphosate at a total        glyphosate a.e. concentration not less than about 360 g/l,        wherein (a) the glyphosate is in anionic form accompanied by low        molecular weight non-amphiphilic cations in a total molar amount        of about 110% to about 120% of the molar amount of glyphosate;        and (b) a major amount to substantially all of the low molecular        weight non-amphiphilic cations are potassium cations; and    -   (iii) a second aqueous concentrate herbicidal composition        comprising in aqueous solution one to a plurality of salts of        the phenoxy-type herbicide, in an amount providing a glyphosate        to phenoxy-type herbicide a.e. ratio of about 1:5 to about 20:1.

Order of addition is not narrowly critical, but it is generally goodpractice to add a portion, for example about one-fourth to aboutthree-fourths, of the water to the vessel and commencing agitationbefore adding the first and second herbicide compositions. The remainderof the water can then be added to make up the desired spray volume.Where ammonium sulfate is to be used, it is generally best to add thisbefore adding the herbicide compositions to ensure complete dissolutionof the ammonium sulfate. Other additives such as a surfactant, ananti-foam agent and/or a drift reduction additive should also be addedto the first portion of water before adding the herbicide compositions.

An illustrative procedure, using spray equipment having a spray tankhaving a filling port and a by-pass line, is as follows.

A 20 to 35 mesh screen is placed over the filling port. Through thescreen, the spray tank is filled to about one-half the desired finalvolume with water, and agitation is started.

If ammonium sulfate is used, this is added slowly through the screeninto the tank. Agitation is continued. No other materials are addeduntil the ammonium sulfate is completely dissolved. A drift reductionadditive, if desired, can now be added.

The first (glyphosate) and second (phenoxy-type) aqueous concentrateherbicide compositions are added, in either order or simultaneously,with continued agitation, optionally while adding the remainder of thewater. The spray tank is filled with the remaining water to the desiredfinal volume.

Good agitation should be maintained until and during spraying. Theby-pass line should be kept near the bottom of the tank to minimizefoaming. Screens in spray nozzles or in-line strainers should be nofiner than 50 mesh.

Further information on preparation and application of tank-mixes can befound, for example, in the product label for Roundup WeatherMAX®herbicide of Monsanto Company, St Louis, Mo. (EPA Reg. No. 524-537),available for example athttp://www.monsanto.com/monsanto/us_ag/content/croppro/roundup_weathermax/label.pdf and incorporated in its entirety hereinby reference.

In a further embodiment of the invention, a method is provided forimproving compatibility of an aqueous concentrate glyphosate potassiumsalt composition with an aqueous concentrate phenoxy-type herbicide saltcomposition when admixed with water to form a tank-mix composition, themethod comprising adding a base in an amount sufficient to raise pH ofthe tank-mix composition to at least about 4.8.

According to this embodiment, the base can be added to the glyphosatecomposition, for example as described hereinbelow. Alternatively, thebase can be added to the phenoxy-type herbicide salt composition.Alternatively, the base can be added during preparation of the tank-mixcomposition itself. Any combination of two or more of these threeoptions for addition of base can be used.

Any convenient base can be used. For adding to the glyphosatecomposition, potassium hydroxide is an option but better results may beobtained with a low molecular weight organic amine such asmonoethanolamine or especially isopropylamine. For adding to thephenoxy-type herbicide composition, a suitable option is to add a basesupplying the same cationic species as used to prepare the herbicidesalt; for example, in the case of the dimethylammonium salt of 2,4-D,additional dimethylamine can be added. For adding to the tank-mixcomposition in the field to prevent precipitation from occurring,suitable bases include without limitation sodium hydroxide, potassiumhydroxide, aluminum hydroxide, ammonia, sodium bicarbonate, ammoniumbicarbonate, etc.

There are practical limitations to the amount of base that can be addedto either of the herbicide compositions. For example, adding enough baseto the aqueous concentrate glyphosate potassium salt composition toprovide a tank-mix composition pH above about 5 can compromise stabilityof the aqueous concentrate formulation, particularly where a surfactantis included in the formulation. However, no such limitation exists foradding a base to the tank-mix composition itself. Illustratively, atank-mix composition pH of about 5 to about 7 can provide good results.A pH higher than about 7 can also be acceptable, but as pH increasesthere can be a tendency for the composition to release ammonia or a lowmolecular weight organic amine such as IPA or DMA, resulting in a strongodor and possible hazard. A base can be added at any stage during orafter admixing of the other ingredients of the tank-mix composition.

It will be understood that the lower the pH of the tank-mix compositionwithout added base, the more base should be added to ensure the pH isbrought into a desirable range. Where ammonium sulfate is present in thetank-mix composition, for example to counteract effects of hard water,compatibility of a glyphosate potassium salt formulation and a 2,4-Ddimethylammonium salt (or other phenoxy-type herbicide salt) formulationcan be further compromised, especially at low spray volumes and/orrelatively high 2,4-D rates. In such situations, a greater amount ofbase may be required.

Illustratively, tank-mix compatibility problems when a glyphosatepotassium salt formulation such as Roundup® Original Max of MonsantoCompany is mixed with a 2,4-D dimethylammonium salt formulation can beameliorated by adding to the tank-mix composition a readily availablebase such as household ammonia (5% aqueous ammonia) or baking soda(sodium bicarbonate), in an amount sufficient to raise pH of thecomposition to about 5 or higher, for example about 5.2 or higher.Suitable pH targets are, for illustrative purposes only, about 5.5,about 5.7, about 5.9, about 6.1, about 6.3 or about 6.5. For example,where a spray volume of 46.8 l/ha (5 U.S. gallons/acre) is used,precipitation of solids can generally be substantially prevented byaddition of household ammonia in an amount of about 4% by volume of thespray solution or by addition of baking soda in an amount of about 10g/l. Lesser amounts of base, for example household ammonia at as littleas 0.75% by volume of the spray solution, can be effective in manysituations.

As compatibility problems tend to increase with increasing 2,4-D rate, asuitable amount of base for addition can be tied to the amount of the2,4-D formulation to be included in the tank-mix composition. Forexample, household ammonia can illustratively be added in avolume/volume ratio to the 2,4-D formulation of about 0.5:1 to about2.5:1, e.g., about 1:1 to about 1.25:1, with a ratio higher in the rangebeing desirable at lower spray volumes. As a further example, bakingsoda can illustratively be added in an amount of about 100 to about 400g, e.g., about 150 to about 250 g, per liter of the 2,4-D formulation.Ratios or amounts outside the ranges given above can also be useful inparticular situations.

In situations where adequate measures have not been taken to preventformation of a precipitate, tank-mixing aqueous concentrate glyphosatepotassium salt and phenoxy-type herbicide compositions can, as indicatedabove, result in formation of a precipitate. In a still furtherembodiment of the invention, a method is provided for redissolving sucha precipitate, the method comprising adding a base in an amountsufficient to redissolve the precipitate.

Suitable bases include without limitation those indicated above asuseful for use in the field to prevent precipitation from occurring,e.g., sodium hydroxide, potassium hydroxide, ammonia, sodiumbicarbonate, ammonium bicarbonate, etc. Upon appearance of aprecipitate, the base should be added with sufficient agitation toredisperse any settled precipitate and prevent further settlement.Suitable amounts of base can be similar to those indicated above, but insome situations a greater amount of base may be needed to redissolve aprecipitate than to prevent the precipitate from occurring in the firstplace.

As a yet further embodiment of the invention, a process is provided forpreparing an aqueous concentrate glyphosate salt composition. Theprocess comprises:

-   -   (i) neutralizing glyphosate acid with potassium hydroxide and        optionally a minor amount of a low molecular weight organic        amine in presence of water to produce a slurry or concentrated        glyphosate salt solution having a pH of about 4.4 to about 4.7;    -   (ii) adding water if necessary and optionally at least one        surfactant to produce a composition having a total glyphosate        a.e. concentration not less than about 360 g/l; and    -   (iii) adding a low molecular weight organic amine in an amount        sufficient to provide a pH of about 4.8 to about 5.0 in the        composition.        The low molecular weight organic amine can be added before,        during or after addition of the water to produce the final        composition.

Low molecular weight organic amines such as isopropylamine can bedifficult or hazardous to handle, and, where it is desired to adjust pHas the final step in the process, it will often be found more convenientto add the organic amine when forming the glyphosate salt at an earlystage of the process, and to use potassium hydroxide (KOH) for pHadjustment. In such a situation, the process comprises:

-   -   (i) neutralizing glyphosate acid with potassium hydroxide and a        minor amount of a low molecular weight organic amine in presence        of water to produce a slurry or concentrated glyphosate salt        solution having a pH of about 4.4 to about 4.7;    -   (ii) adding water if necessary and optionally at least one        surfactant to produce a composition having a total glyphosate        a.e. concentration not less than about 360 g/l; and    -   (iii) adding potassium hydroxide in an amount sufficient to        provide a pH of about 4.8 to about 5.0 in the composition.

The low molecular weight organic amine used in the process canillustratively be methylamine, dimethylamine, propylamine (e.g.,n-propylamine or isopropylamine), mono-, di- or triethanolamine. In oneembodiment the low molecular weight organic amine is isopropylamine.

Where the composition to be prepared comprises a minor amount of a lowmolecular weight organic ammonium salt of glyphosate, the followingnonlimiting process can be used.

In a first step, glyphosate acid is added to a glyphosate potassium saltsolution having a glyphosate assay of at least about 40% a.e. by weight,to form a slurry. In a second step, isopropylamine, in an amount atleast sufficient to neutralize the added glyphosate acid and to providea base excess of about 10% to about 20% in the composition as a whole,is introduced to the slurry with mixing until all glyphosate isdissolved, to form a mixed glyphosate salt solution comprising potassiumand IPA cations in the desired mole ratio. Neutralization of glyphosateacid is exothermic and it will generally be desirable to make provisionfor heat removal during the second step of this process.

The glyphosate acid can be added in substantially dry form or,conveniently, in a form of “wet cake”, which can typically contain up toabout 15% by weight of water.

If desired, another low molecular weight organic amine such asn-propylamine can be substituted for isopropylamine. Especially wherevery high glyphosate a.e. concentration (for example greater than about540 g/l) is desired in the final product, it is desirable to useisopropylamine in anhydrous form, to avoid introducing more water thannecessary.

Relative amounts of potassium salt, glyphosate acid and isopropylamineare selected to provide a mixed glyphosate salt solution having a baseexcess of about 10% to about 20% and a desired mole ratio of potassiumto IPA cations, for example of about 55:45 to about 99:1, or about 60:40to about 99:8. In one exemplary embodiment, the mole ratio is about70:30 to about 90:10, for example about 75:25 to about 85:15, or about77:23 to about 83:17, illustratively about 80:20. In another exemplaryembodiment, the mole ratio is about 95:5 to about 99:1, for exampleabout 96:4 to about 98:2, illustratively about 97:3.

In an optional further step of the process, water and optionallysurfactant can be added to the mixed glyphosate salt solution to adjustglyphosate a.e. concentration of the mixed salt solution to a desiredlevel not less than about 360 g/l, for example not less than about 400g/l. If desired or necessary, further and final pH adjustment can bemade at this stage to bring the pH into a range of about 4.8 to about 5.Suitably, such final pH adjustment can be made with potassium hydroxide.

One of skill in the art will be able to design a protocol to determinewhether a glyphosate potassium salt test composition as provided hereinexhibits improved tank-mix compatibility with a phenoxy-type herbicidesalt composition. One illustrative protocol, for use where thephenoxy-type herbicide salt is a salt of 2,4-D and compatibility is tobe tested at a low spray volume of 5 gallons/acre (47 l/ha) in presenceof ammonium sulfate, is presented below.

Water of known hardness (e.g., 1,000 ppm) in an amount of 94.17 ml isadded to a suitable vessel such as a 100 ml jar or beaker and agitatedwith a magnetic stir bar. Ammonium sulfate in an amount of 0.41 g isadded. Once all the ammonium sulfate has dissolved, 3.33 ml of theglyphosate formulation and 2.5 ml of the 2,4-D formulation are added tobring the total volume of the resulting solution to 100 ml, and the timeis noted.

Agitation is continued for the duration of the test (e.g., 12 hours) andthe solution is examined at intervals. The time at which formation of aprecipitate is first observed is recorded.

The volumes of the glyphosate and 2,4-D formulations given abovecorrespond to a glyphosate formulation concentration of 540 g a.e./lapplied at a rate of 1.33 pint/acre (1.56 l/ha), equivalent to 0.75 lba.e./acre (0.84 kg a.e./ha); and a 2,4-D formulation applied at a rateof 1 pint/acre (1.17 l/ha). These volumes can be adjusted to simulateother application rates of glyphosate and 2,4-D, and the volume of waterinitially added can be adjusted accordingly.

Similarly, the amounts of the various ingredients added can readily beadjusted to simulate other spray volumes and other ammonium sulfateconcentrations.

The invention is further illustrated but not limited by the followingExamples.

EXAMPLES Example 1

Tank mixtures of a commercial glyphosate potassium salt formulation(Roundup® Original Max of Monsanto Company) and a commercial 2,4-Ddimethylammonium salt formulation (Agrisolution™ 2,4-D Amine ofAgriliance LLC) were simulated by adding the following ingredients inthe order shown to a 100 ml Nessler tube, with mixing by inversion:

1. 60 ml water, 342 ppm hardness;

2. 0-4 ml (see below) 5% aqueous ammonia;

3. 5.26 ml 2,4-D formulation;

4. water, 342 ppm hardness, q.s. for final volume of 100 ml;

5. 3.33 ml glyphosate formulation.

The volumes of ingredients were calculated to simulate a tank mixturefor low spray volume (5 U.S. gallons/acre, or about 46.8 l/ha).

Without addition of aqueous ammonia, flocculation of solids occurredimmediately and settled quickly. Solids could be resuspended byagitation, but would not dissolve.

In presence of up to 1 ml of 5% aqueous ammonia, no improvement inflocculation was observed. With increase in ammonia to 1.5 ml,flocculation was noticeably slower. In presence of 2-3.5 ml ammonia,flocculation took approximately 3-5 minutes to begin, and in presence of4 ml ammonia, no flocculation occurred.

Example 2

Simulated tank mixtures were prepared as in Example 1, but with volumesof ingredients calculated to simulate 10 U.S. gallons/acre (about 93.5l/ha), as follows:

1. 60 ml water, 342 ppm hardness;

2. 0-4 ml 5% aqueous ammonia;

3. 2.63 ml 2,4-D formulation;

4. water, 342 ppm hardness, q.s. for final volume of 100 ml;

5. 1.67 ml glyphosate formulation.

Without addition of aqueous ammonia, no flocculation of solids occurredimmediately, but a precipitate appeared after about 1 hour.Precipitation was unaffected by addition of 0.5 ml of 5% aqueousammonia, but in presence of 1 ml or more ammonia, no precipitation wasobserved.

Example 3

Tank mixtures of glyphosate potassium salt (Roundup® Original Max) and2,4-D dimethylammonium salt (Agrisolution™ 2,4-D Amine) were simulatedby adding the following ingredients in the order shown to a 600 mlbeaker, with mixing using a stir plate:

1. 366 ml water, 342 ppm hardness;

2. 20 ml 2,4-D formulation;

3. 13 ml glyphosate formulation.

Heavy precipitation was observed. After a 5 minute period to allow fulldevelopment of the precipitate, 5% aqueous ammonia was added in 5 mlincrements every 2 minutes.

Redis solution of the precipitate became evident by a degree of clearingof the solution after addition of 20 ml ammonia, but full redissolutionrequired at least 25 ml ammonia. Even then, the solution remainedslightly hazy.

Example 4

A precipitate formed by preparing a simulated tank mixture of glyphosatepotassium salt (Roundup® Original Max) and 2,4-D dimethylammonium salt(Agrisolution™ 2,4-D Amine) was collected on filter paper. The resultingcrystalline white solid was insoluble in acetone but soluble in water,providing a solution pH of 3.3. Analysis by NMR gave results that,together with the pH data, suggested that the precipitate was composedof about 70% 2,4-D potassium salt and about 30% 2,4-D acid. No more thantraces of glyphosate or surfactant were evident.

Example 5

A simulated tank mixture was prepared in a Nessler tube with volumes ofingredients calculated to simulate 5 U.S. gallons/acre (about 46.8l/ha), using the same glyphosate and 2,4-D formulations as above, withagitation as follows:

1. 91.67 ml water, 342 ppm hardness;

2. 0.5 g sodium bicarbonate;

3. 3.33 ml glyphosate formulation;

4. 5 ml 2,4-D formulation.

A clear solution was produced. No precipitation formed up to 30 minutesafter preparation.

Example 6

A simulated tank mixture was prepared in a Nessler tube with volumes ofingredients calculated to simulate 5 U.S. gallons/acre (about 46.8l/ha), using the same glyphosate and 2,4-D formulations as above, withagitation as follows:

1. 91.67 ml water, 342 ppm hardness;

2. 3.33 ml glyphosate formulation;

3. 5 ml 2,4-D formulation.

A precipitate formed within 30 seconds. Sodium bicarbonate was added inan amount of 0.5 g. Slight clearing of the solution was noted. Withaddition of a further 0.5 g sodium bicarbonate (total 1 g), the solutioncleared quickly as the precipitate dissolved.

Example 7

Aqueous concentrate formulations (compositions 7-2 to 7-5) of glyphosatepotassium salt were prepared at a glyphosate a.e. loading of 540 g/l,containing about 100 g/l of the surfactant of formula (VII) above andabout 0.5 g/l of a silicone antifoam agent. An organic amine base,monoethanolamine (MEA), isopropylamine (IPA), triisopropylamine (TIPA)or dimethylethanolamine (DMEA) was added in an amount of 1% or 2% byweight to upwardly adjust pH of the formulation. A formulation withoutadded base (composition 7-1) was prepared as a reference standard.

Cloud point of each pH-adjusted formulation was measured. A simulatedtank-mix compatibility test was conducted for each formulation. Volumesof ingredients were calculated to simulate a spray volume of 5 U.S.gallons/acre (about 46.8 l/ha), a glyphosate a.e. rate of 0.75 lb/acre(about 0.84 kg/ha) and a 2,4-D formulation (Agrisolution™ 2,4-D Amine,Loveland™ 2,4-D Amine 4 or Saber™ herbicide of Loveland Products, Inc.)rate of 1 U.S. pint/acre (about 1.17 l/ha). Ingredients were added to aNessler tube with agitation as follows:

1. 94.17 ml water, 1000 ppm hardness;

2. 3.33 ml glyphosate formulation;

3. 2.5 ml 2,4-D formulation.

Compatibility was measured by the length of time it took for aprecipitate to begin forming in the tube. Results are shown in Table 1.

TABLE 1 Compatibility of glyphosate compositions with 2,4-D Base Cloud2,4-D Time to form Composition added point formulation precipitate 7-1none Agrisolution precipitate formed immediately 7-2 MEA 1%   54° C.  5min 7-3 MEA 2% <45° C. 40 min 7-4 IPA 1%   58° C. 10 min 7-5 IPA 2% <50°C. >2 h (solution hazy) 7-1 none Loveland 45 sec 7-6 TIPA 1%   66° C.  2min 7-7 TIPA 2%   62° C.  2 min 7-8 DMEA 1%   58° C. 15 min 7-9 DMEA 2%<55° C. 60 min 7-1 none Saber 20 min 7-6 TIPA 1%   66° C. 90 min 7-7TIPA 2%   62° C. >2 h (solution cloudy) 7-8 DMEA 1%   58° C. >2 h(solution cloudy) 7-9 DMEA 2% <55° C. >2 h (solution cloudy)

Example 8

Glyphosate potassium salt formulations having added IPA to improvecompatibility with 2,4-D were further modified (compositions 8-1 to 8-5)by addition to or partial substitution of the surfactant of formula(VII) (“surfactant VII”) with polyoxyethylene (2) cocoamine surfactant(“coco-2”), or by use of a surfactant system comprising polyoxyethylene(10.5) tallowamine (“tallow-10.5”) and coco-2 (compositions 8-6 and8-7), in an effort to increase cloud point, as detailed in Table 2.

TABLE 2 Modified potassium glyphosate formulations CompositionIngredients¹ Weight % Loading (g/I) Cloud point 8-1 glyphosate K salt²84.0 540 65° C. surfactant VII 7.5 102 coco-2 2.5 34 IPA 1.0 8-2glyphosate K salt² 84.0 540 62° C. surfactant VII 7.5 102 coco-2 1.25 17IPA 1.0 8-3 glyphosate K salt² 84.0 540 57° C. surfactant VII 6.0 82coco-2 1.5 20 IPA 2.0 8-4 glyphosate K salt² 84.0 540 55° C. surfactantVII 6.4 87 coco-2 1.1 15 IPA 2.0 8-5 glyphosate K salt² 84.0 540 52° C.surfactant VII 6.8 92 coco-2 0.8 10 IPA 2.0 8-6 glyphosate K salt³ 83.0540 54° C. tallow-10.5 7.0 95 coco-2 3.0 41 IPA 1.0 8-7 glyphosate Ksalt³ 83.2 540 62° C. tallow-10.5 6.0 81 coco-2 2.6 35 IPA 1.0 ¹siliconeantifoam agent (in most cases 0.05%) not shown; balance to 100% is water²concentrated aqueous solution, glyphosate assay 47.2% a.e.³concentrated aqueous solution, glyphosate assay 47.9% a.e.

A simulated tank-mix compatibility test similar to that of Example 7 wasconducted for each of compositions 8-1 to 8-7, by comparison withcomposition 7-1 as a reference standard. Volumes of ingredients werecalculated to simulate a spray volume of 5 U.S. gallons/acre (about 46.8l/ha), a glyphosate a.e. rate of 0.75 lb/acre (about 0.84 kg/ha) and a2,4-D formulation (UCPA™ 2,4-D Amine 4 or Agrisolution™ 2,4-D Amine)rate of 1 U.S. pint/acre (about 1.17 l/ha), together with ammoniumsulfate, 4.1 g/l. Results are shown in Table 3.

TABLE 3 Compatibility of glyphosate compositions with 2,4-D Composition2,4-D formulation Time to form precipitate 7-1 UCPA  1 min 8-1 >40 min(solution clear) 8-2  10 min 8-3 >40 min (solution clear) 8-4 >40 min(solution clear) 8-5 >40 min (solution clear) 8-6 >40 min (solutionclear) 8-7  20 min 7-1 Agrisolution  1.3 min 8-1 59.2 min 8-2 11.6 min8-3 34.2 min 8-4 56.2 min 8-5 57.6 min 8-6 73.3 min 8-7 19.8 min

Example 9

Glyphosate formulations (compositions 9-1 to 9-5) comprising a mixtureof potassium and IPA salts at a 70/30 weight/weight ratio and variousblends of tallow-10.5 and coco-2 were prepared, with addition of IPA toraise pH to 4.9 or higher, as detailed in Table 4. Cloud point and pHwere determined for each formulation.

Measurement of pH was according to the following protocol. A 6.6 gsample of the formulation was weighed into a 150 ml beaker.Demineralized water was added to make a total solution mass of 100 g.The solution was agitated with a magnetic stirring bar. A pH metercapable of measuring pH to 2 decimal places, and fitted with anelectrode with temperature compensation, was used for the measurement.The pH meter was calibrated with standard buffers at pH 4.0 and pH 7.0.The solution pH was recorded when a reading was obtained that was stablefor at least 10 seconds. Between sample measurements, the electrode waswashed with and stored temporarily in demineralized water. After allsample measurements, the calibration was rechecked against the pH 4.0and pH 7.0 buffers. If significant drift was observed, the electrode wasrecalibrated, and pH of all samples measured again. After allmeasurements were complete, the electrode was washed thoroughly withdemineralized water, and placed in a 1M KCl solution for long termstorage.

TABLE 4 Modified glyphosate formulations Loading Cloud CompositionIngredients¹ Weight % (g/I) pH point 9-1 glyphosate K/IPA salt² 86.8 5404.90 69° C. tallow-10.5 7.3 96 coco-2 1.8 24 IPA 1.0 9-2 glyphosateK/IPA salt² 86.8 540 4.99 62° C. tallow-10.5 7.3 96 coco-2 1.8 24 IPA1.5 9-3 glyphosate K/IPA salt² 86.8 540 4.92 72° C. tallow-10.5 6.8 90coco-2 2.3 30 IPA 1.0 9-4 glyphosate K/IPA salt² 86.8 540 4.96 66° C.tallow-10.5 6.8 90 coco-2 2.3 30 IPA 1.5 9-5 glyphosate K/IPA salt² 86.8540 5.06 59° C. tallow-10.5 6.8 90 coco-2 2.3 30 IPA 2.0 ¹siliconeantifoam agent (0.038%) not shown; balance to 100% is water²concentrated aqueous solution, glyphosate assay 47.2% a.e.

A simulated tank-mix compatibility test similar to that of Example 7 wasconducted for each of compositions 9-1 to 9-5, by comparison withRoundup® Original Max and Roundup® WeatherMAX® herbicides as referencestandards. Volumes of ingredients were calculated to simulate a sprayvolume of 5 U.S. gallons/acre (about 46.8 l/ha), a glyphosate a.e. rateof 0.75 lb/acre (about 0.84 kg/ha) and a 2,4-D formulation (UCPA™ 2,4-DAmine 4) rate of 1 U.S. pint/acre (about 1.17 l/ha), together withammonium sulfate, 4.1 g/l. Results are shown in Table 5.

TABLE 5 Compatibility of glyphosate compositions with 2,4-D CompositionTime to form precipitate Roundup Original Max  1 min Roundup WeatherMAX10 min 9-1 >3 h, <24 h 9-2 >3 h, <24 h (precipitate very light) 9-3 >3h, <24 h 9-4 >3 h, <24 h (precipitate very light) 9-5 >24 h (solutionclear)

Example 10

Glyphosate formulations (compositions 10-1 to 10-8), comprisingpotassium salt or potassium and IPA salts at a 70/30 weight/weightratio, and various blends of tallowamine and coco-2 were prepared, withaddition of IPA or 45% KOH to raise pH to 4.88 or higher, as detailed inTable 6. Cloud point and pH were determined for each formulation. The pHmethod was similar to that described in Example 9.

TABLE 6 Modified glyphosate formulations Loading Cloud CompositionIngredients¹ Weight % (g/I) pH point 10-1 glyphosate K/IPA salt² 86.6540 4.89 69° C. tallow-10.5 7.6 100 coco-2 1.9 25 IPA 1.0 10-2glyphosate K/IPA salt² 86.6 540 4.92 71° C. tallow-10.5 7.4 98 coco-22.5 33 IPA 1.0 10-3 glyphosate K salt³ 84.0 540 4.93 65° C. tallow-8 5.371 coco-2 2.3 30 IPA 1.5 10-4 glyphosate K salt³ 84.0 540 4.96 64° C.tallow-8 5.5 75 coco-2 3.0 40 IPA 1.5 10-5 glyphosate K salt³ 84.0 5404.94 70° C. tallow-9 4.5 61 coco-2 3.0 41 IPA 1.5 10-6 glyphosate Ksalt³ 84.0 540 4.96 65° C. tallow-9 5.1 69 coco-2 3.4 46 IPA 1.5 10-7glyphosate K salt³ 84.0 540 4.88 63° C. tallow-9 4.9 66 coco-2 4.0 5445% KOH 2.0 10-8 glyphosate K salt³ 83.7 540 4.90 63° C. tallow-9 4.7 63coco-2 3.8 52 45% KOH 2.25 ¹silicone antifoam agent (0.038%) not shown;balance to 100% is water ²concentrated aqueous solution, glyphosateassay 47.2% a.e. ³concentrated aqueous solution, glyphosate assay 47.5%a.e.

A simulated tank-mix compatibility test similar to that of Example 7 wasconducted for compositions 10-1 to 10-8, by comparison with Roundup®Original Max herbicide as a reference standard. Also included asstandards were aqueous concentrate compositions of glyphosate potassiumsalt and glyphosate IPA salt, with no surfactant or pH adjustment.Volumes of ingredients were calculated to simulate a spray volume of 5U.S. gallons/acre (about 46.8 l/ha), a glyphosate a.e. rate of 0.75lb/acre (about 0.84 kg/ha) and a 2,4-D formulation (UCPA™ 2,4-D Amine 4)rate of 1 U.S. pint/acre (about 1.17 l/ha), together with ammoniumsulfate, 4.1 g/l. Results are shown in Table 7.

TABLE 7 Compatibility of glyphosate compositions with 2,4-D CompositionTime to form precipitate Roundup Original Max 2 min glyphosate K saltimmediate glyphosate IPA salt >24 h (solution cloudy) 10-1 >9 h, <24 h10-2 >9 h, <24 h (precipitate very light) 10-3 4 h 10-4 >9 h, <24 h 10-57 h 10-6 4 h 10-7 40 min 10-8 1 h 20 min

Example 11

Glyphosate potassium salt formulations (compositions 11-1 to 11-4)comprising various blends of tallow-9 and coco-2 were prepared, withaddition of IPA to raise pH to 4.83 or higher, as detailed in Table 8.Cloud point and pH were determined for each formulation. The pH methodwas similar to that described in Example 9.

TABLE 8 Modified glyphosate potassium salt formulations Loading CloudComposition Ingredients¹ Weight % (g/I) pH point 11-1 glyphosate K salt²83.8 540 5.00 67° C. tallow-9 5.1 69 coco-2 4.2 56 IPA 1.5 11-2glyphosate K salt² 83.8 540 4.99 64° C. tallow-9 5.5 75 coco-2 4.5 61IPA 1.5 11-3 glyphosate K salt² 84.0 540 4.83 65° C. tallow-9 5.3 72coco-2 3.6 48 IPA 1.25 11-4 glyphosate K salt² 84.0 540 4.91 63° C.tallow-9 5.3 72 coco-2 3.6 48 IPA 1.5 ¹silicone antifoam agent (0.038%)not shown; balance to 100% is water ²concentrated aqueous solution,glyphosate assay 47.5% a.e.

A simulated tank-mix compatibility test similar to that of Example 7 wasconducted for each of compositions 11-1 to 11-4, by comparison withRoundup® Original Max herbicide as a reference standard. Also includedwere glyphosate mixed potassium/IPA salt compositions 9-2 and 9-4 fromExample 9. Volumes of ingredients were calculated to simulate a sprayvolume of 5 U.S. gallons/acre (about 46.8 l/ha), a glyphosate a.e. rateof 0.75 lb/acre (about 0.84 kg/ha) and a 2,4-D formulation (UCPA™ 2,4-DAmine 4) rate of 1 U.S. pint/acre (about 1.17 l/ha), together withammonium sulfate, 4.1 g/l. Results are shown in Table 9.

TABLE 9 Compatibility of glyphosate compositions with 2,4-D CompositionTime to form precipitate Roundup Original Max 40 sec  9-2 >9 h (solutioncloudy), <24 h (precipitate light)  9-4 >9 h (solution cloudy), <24 h(precipitate light) 11-1 >9 h (solution clear), <24 h 11-2 >9 h(solution cloudy), <24 h (precipitate light) 11-3 3.5 h 11-4   4 h

Example 12

Glyphosate potassium salt formulations (compositions 12-1 to 12-4)comprising a specific surfactant blend were prepared, with addition ofKOH, monoethanolamine (MEA), triethanolamine (TEA) or ammonia to raisepH to 4.8 or higher, as detailed in Table 10. Cloud point and pH weredetermined for each formulation. The pH method was similar to thatdescribed in Example 9.

TABLE 10 Modified glyphosate potassium salt formulations Loading CloudComposition Ingredients¹ Weight % (g/I) pH point 12-1 glyphosate K salt²83.9 540 4.88 63° C. surfactant blend 8.9 120 45% KOH 2.0 12-2glyphosate K salt² 84.0 540 4.96 60° C. surfactant blend 8.9 120 40% MEA2.0 12-3 glyphosate K salt² 83.9 540 4.88 76° C. surfactant blend 8.9120 TEA 2.47 12-4 glyphosate K salt² 83.9 540 4.80 69° C. surfactantblend 8.9 120 30% aqueous ammonia 2.0 ¹silicone antifoam agent (0.038%)not shown; balance to 100% is water ²concentrated aqueous solution,glyphosate assay 47.5% a.e.

A simulated tank-mix compatibility test similar to that of Example 7 wasconducted for each of compositions 12-1, 12-2 and 12-4, by comparisonwith Roundup® Original Max herbicide as a reference standard. Volumes ofingredients were calculated to simulate a spray volume of 5 U.S.gallons/acre (about 46.8 l/ha), a glyphosate a.e. rate of 0.75 lb/acre(about 0.84 kg/ha) and a 2,4-D formulation (Agrisolution™ 2,4-D Amine)rate of 1 U.S. pint/acre (about 1.17 l/ha), together with ammoniumsulfate, 4.1 g/l. Results are shown in Table 11.

TABLE 11 Compatibility of glyphosate compositions with 2,4-D CompositionTime to form precipitate Roundup Original Max 30 sec 12-1 2.5 h 12-2 >10h, <20 h 12-4 >10 h, <20 h

Example 13

A simulated tank-mix compatibility test similar to that of Example 7 wasconducted for composition 12-3, by comparison with Roundup® Original Maxherbicide as a reference standard. Volumes of ingredients werecalculated to simulate a spray volume of 5 U.S. gallons/acre (about 46.8l/ha), a glyphosate a.e. rate of 0.75 lb/acre (about 0.84 kg/ha) and a2,4-D formulation (Agrisolution™ 2,4-D Amine) rate of 1 U.S. pint/acre(about 1.17 l/ha), together with ammonium sulfate, 4.1 g/l. Results areshown in Table 12.

TABLE 12 Compatibility of glyphosate compositions with 2,4-D Time toform Composition precipitate Roundup Original Max 40 sec 12-3 30 min

Example 14

Glyphosate potassium salt compositions 10-6, 10-8 and 11-1, prepared asabove, were compared with Roundup® Original Max herbicide in varioussimulated tank-mix compatibility tests similar to that of Example 7,wherein water temperature, water hardness and ammonium sulfate levelwere varied. Volumes of ingredients were calculated to simulate a sprayvolume of 5 U.S. gallons/acre (about 46.8 l/ha), a glyphosate a.e. rateof 0.75 lb/acre (about 0.84 kg/ha) and a 2,4-D formulation(Agrisolution™ 2,4-D Amine) rate of 1 U.S. pint/acre (about 1.17 l/ha).Results are shown in Table 13.

TABLE 13 Compatibility of glyphosate compositions with 2,4-D Hardness(NH₄)₂SO₄ Time to form Temp. (ppm) (g/I) Composition precipitate ambient0 0 Roundup Original Max 1 h 10-8 >24 h 10-6 >24 h 11-1 >24 h ambient 04.1 Roundup Original Max 4 min 10-8 >10 h, <20 h 10-6 >24 h 11-1 >24 hambient 342 0 Roundup Original Max 9 min 10-8 >10 h, <24 h 10-6 >24 h11-1 >24 h ambient 342 4.1 Roundup Original Max 5 min 10-8 >24 h10-6 >24 h 11-1 >24 h ambient 1000 0 Roundup Original Max 5 min 10-8 6 h35 min 10-6 6 h 20 min 11-1 3 h 38 min ambient 1000 5 Roundup OriginalMax 1.5 min 10-8 2 h 10-6 8-10 h 11-1 8-10 h ambient 1000 10 RoundupOriginal Max 40 sec 10-8 10 min 10-6 9-10 h 11-1 9-10 h 10° C. 1000 0Roundup Original Max 1.5 min 10-8 11.5 min 10-6 21 min 11-1 17 min 10°C. 1000 4.1 Roundup Original Max 2 min 10-8 11 min 10-6 15 min 11-1 20min  4° C. 1000 4.1 Roundup Original Max 3 min (heavy precipitate) 10-817 min (light precipitate) 10-6 16 min (light precipitate) 11-1 11 min(heavy precipitate)

What is claimed is:
 1. A herbicidal composition comprising an aqueoussolution of a plurality of salts of glyphosate wherein (a) saidglyphosate is in anionic form accompanied by low molecular weightnon-amphiphilic cations; (b) a major amount but less than 100% of thelow molecular weight non-amphiphilic cations are potassium cations; and(c) the composition has a measured pH of at least about 4.8.
 2. Thecomposition of claim 1, having a measured pH of about 4.8 to about
 7. 3.The composition of claim 1, having a measured pH of about 4.8 to about6.
 4. The composition of claim 1, having a total glyphosate a.e.concentration of about 360 to about 650 g/l.
 5. The composition of claim1, having a total glyphosate a.e. concentration of about 400 to about600 g/l.
 6. The composition of claim 1, being an application solutionhaving a total glyphosate a.e. concentration of about 0.1 to about 100g/l.
 7. The composition of claim 1, wherein the balance to 100% of thelow molecular weight non-amphiphilic cations is provided in part or inwhole by low molecular weight organic ammonium cations.
 8. Thecomposition of claim 7, having a mole ratio of potassium to lowmolecular weight organic ammonium cations of about 55:45 to about 99:1.9. The composition of claim 7, wherein said low molecular weight organicammonium cations comprise isopropylammonium cations.
 10. The compositionof claim 1, further comprising at least one surfactant.
 11. Thecomposition of claim 10, wherein the weight ratio of glyphosate a.e. tototal surfactant is not greater than about 10:1.
 12. The composition ofclaim 1, further comprising a phenoxy-type herbicide salt.
 13. Thecomposition of claim 12, wherein the phenoxy-type herbicide is selectedfrom the group consisting of phenoxyacetic acids, phenoxypropanoicacids, phenoxybutanoic acids, benzoic acids, picolinic acids,pyridinyloxyacetic acids and enantiomers and racemates thereof.
 14. Thecomposition of claim 12, wherein the phenoxy-type herbicide is selectedfrom the group consisting of 2,4-D, dicamba and picloram.
 15. Thecomposition of claim 12, wherein the phenoxy-type herbicide salt is apotassium, sodium, ammonium or organic ammonium salt.
 16. Thecomposition of claim 12, wherein the phenoxy-type herbicide salt isselected from the group consisting of methylammonium, dimethylammonium,n-propylammonium, isopropylammonium, mono-, di- and triethanolammoniumsalts.
 17. The composition of claim 12, wherein the phenoxy-typeherbicide salt is the dimethylammonium salt of 2,4-D.
 18. Thecomposition of claim 12, having a glyphosate/phenoxy-type herbicide a.e.ratio of about 1:5 to about 20:1.